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<!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML//EN">
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<head>
<title>AMR-UCD Reader</title>
</head>
<body bgcolor="#F0F0F0">
<h1>AMR-UCD Reader</h1>
Most visualization systems have no provisions for handling AMR
data. One solution is to resample all of the grids into a single
uniform sized grid. However for even a 7 level hierarchy, the
unigrid becomes far too large to be manageable and still retain
the fidelity of the original data. A second solution is use
unigrid visualization algorithms on each grid in the hierarchy and
then superimpose them on one-another. In this case geometries
from the coarser resolution datasets occlude the finer-resolution
geometry. An alternative solution is to convert the data into
hexahedral cells with the overlaps between parent levels and the
children are eliminated. This provides multi-resolution fidelity which
matches the nature of the original data but allows it to be
visualized using standard off-the-shelf visualizaton tools.<p>
The <code>AmrUcdFileReader</code> inherits directly from the
<code><a href="AMRfileReader.html">AmrFileReader</a></code> and
all methods from its base class are public. They will be
listed again here for convenience. The only method (aside from
the constructor/destructor) that is contributed by this class is
the <a name="#GETUCD">getUcd()</a> method.<p>
<hr>
<font face="arial,helvetica" color="#555588"><h2>The API</h2></font>
<UL>
<LI><a href="#CPP">C++ Interface</a>
<LI><a href="#C">C Interface</a>
<LI><a href="#F77">F77/F90 Interface</a>
</UL>
<hr>
<u><h3><a name="CPP">C++ Interface</a></h3></u>
<DL>
<DT><font color="#888888"><b>Constructors/Destructors</b></font>
<DL>
<DT><b>AmrUcdFileReader::AmrUcdFileReader(IObase
&filehandle)</b> <i>constructor</i>
<DD>The <i>filehandle</i> is an already
<a href="UsingC++.html#Opening">open IEEEIO or HDFIO
file</a>. This initializes the reader and attaches it to that
datafile.
<DT><b>AmrUcdFileReader::~AmrUcdFileReader()</b> <i>destructor</i>
<DD>This flushes all of the necessary file buffers.
The filehandle that the reader was bound to must be
closed separately though.
</DL>
<DT><font color="#888888"><b>Queries about File Contents</b></font>
<DL>
<DT><b>int AmrUcdFileReader::nLevels()</b>
<DD>Returns the number of levels in the AMR hierarchy. This is
the deepest the hierarchy gets in this particular datafile as
opposed to the number of levels present at this time in the
evolution (this distinction is important for adaptive depth
schemes where the number of levels will change depending on
the demands of the solver).
<DT><b>AmrUcdFileReader::getTimeRange(int &mintime,int &maxtime)</b>
<DD>Gets the range of integer timesteps stored in the file.
The nonzero mintime exists to support schemes where the
evolution is broken up among several files.
</DL>
<DT><font color="#888888"><b>Filters</b></font>
<DT>The <i><b>filter</b></i> methods listed below select grids based on
the criteria of time and level number. Grids selected by the
filter are referred to as <i><b>active grids</b></i>.<p>
<DL>
<DT><b>AmrUcdFileReader::setTime(int time)</b>
<DD>Sets the current timestep to select the data hierarchy for.
The timestep is defined with respect to the rate at which
grids change at the deepest level of the AMR hierarchy stored
in the file. Selecting a particular timestep selects a
snapshot of the hieararchy at a particular time in the
evolution.
<DT><b>AmrUcdFileReader::hideLevel(int level)</b>
<DD>By default all levels are visible and are read in when the
<code>getGrids()</code> method is called. You can hide
individual levels using this method. This is useful when
loading the entire hierarchy is either too confusing, too slow, or too
large for the workstation to handle.
<DT><b>AmrUcdFileReader::showLevel(int level)</b>
<DD>Shows a level that has otherwise been hidden.
<DT><b>AmrUcdFileReader::showAllLevels()</b>
<DD>A convenience method for making all of the levels visible.
</DL>
<DT><font color="#888888"><b>Getting the UCD Data</b></font>
<DL>
<DT><b>int AmrUcdFileReader::getUcd(FlexArray<AmrNode*>
&nodes, FlexArray<int> &cells)</b>
<DD>Gets all currently active grids and converts them into a
finite element form composed of hexahedral cells. The node
list contains the coordinates of the vertices of the cells and
the cell list contains the connectivity of the hexahedral
cells (indexed into the nodes list where the first element is
an index of <i>0</i> and the last is <i>NumNodes-1</i>).
</DL>
<DT><font color="#888888"><b>Utility and Debugging Methods</b></font>
<DT><DL>
<DT><b>AmrUcdFileReader::setDataLoadingOff()</b>
<DD>This causes the <code>getGrids()</code> methods
to read in the informational part of
the AmrGrid datastructures, but not load any data. This is
useful for just aquiring bounding box information or
estimating the memory/computational requirements for loading
the entire hierarchy.
<DT><b>AmrUcdFileReader::setDataLoadingOn()</b>
<DD>This causes the <code>getGrids()</code> methods
to read both the informational and data part of
the AmrGrid datastructures. This is the default state for
this API.
<DT><b>printGridInfo()</b>
<DD>Prints information about all grids in file to STDERR. Used
only for debugging.
<DT><b>printActiveGrids()</b>
<DD>Prints information about all <b>active</b> grids to STDERR.
Used only for debugging.
<DT><b>int debug</b>
This is a public variable that can be set to a nonzero value
in order to print additional debugging information for each
method call. This printing is turned off when it is set to zero.
</DL>
</DL>
<hr>
<h3><u><a name="C">C Interface</a></u></h3>
Not ready yet.
<hr>
<h3><u><a name="F77">F77/F90 Interface</a></u></h3>
Not ready yet.
<hr>
<address><a href="mailto:jshalf@ariel.ncsa.uiuc.edu"></a></address>
<!-- Created: Thu Feb 4 20:37:32 CST 1999 -->
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Last modified: Thu Feb 4 21:31:06 CST 1999
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